Teletypewriter control system



May l, 1945. R. J. ANSPACH ET AL I TELETYPEWRITER CONTROL SYSTEM Filed Jan. 12, 194s INVENTORS Patented May 1, 1945 TELETYPEWRITER ooNrRoL SYSTEM Kessel! Jacob nsnah, Westfield, and Charles Robert Walker, Jersey City. N. l... assigning i American Telephone and V'Ielegraph Company,V

a corporation of New York Application January 12, 1943, Serial No. 472,092

(ci. ivsfii) 4 Claims.

This invention relates to electrical control systems. More particularly this invention relates to telegraph and teletypewriter signaling systems and to arrangements for the control of motor and other apparatus which may be employed in such systems.

In prior teletypewriter systems, for example, in which a plurality of stations are interconnected so that any one of the stations may transmit signals to any one or more of the other stations, it has been the practice to operate the motors of the teletypewriter equipment at all stations which are connected to the` circuit even though but one of the -stations is expected to receive the signals.

Although the teletypewriter at. one of the stations is alone receiving the signals, the motors at all of the other teletypewriter staticils Connected to the System are run continuously. This involves a Wattage. of power, an unnecessary deterioration of the Operating parts of the motors and other allied n equipment, and at the seme time produces considerable noise.

In order to overcome the difculties of prior art systems it is proposed to interconnect two or more stations for vthe transmission of teletypewriter (or like) signals so that the motor at any receiving station will be operated only when signals are to be transmitted to that station. In accordance with one embodiment of the invention to be described hereinaiter a predetermined signal will be transmitted in order to cause the source of power to be connected to the motor at a receiving teletypewriter station and the system is arranged so that the motor at the receiving station will remain in operation until a subsequent signal is transmitted to cause its disconnection from its source Cil of power. lThe signal pulses themselves will be -I employed to maintain the motor apparatus in operation.

In the specific embodiment of the invention to be described hereinafter, two stations may be interconnected for the transmission of signals from one of the stations to the other station and the receiving station will include a, relay connected to the receiving loop through a full-wave rectiiier, the relay controlling the connection of the motor of the associated teletypewriter apparatus to the power source. The full-,wave rectiiier will he employed to ,convert the pulses characteristic of teletypewriter signals into unidirectional or nonpulsating currents which will flow through the relay winding and act to. maintain the motor of thel receiving teletypewriter connected to its source of power. The relay will remain operated as long as either of the two, oppositely poled po.-

tentials are appliedto the telegraph loop. This will be explained in greater detail hereinafter.

This invention will be better understood from the more detailed description hereinafter following, when read in connection with the accompany-- ing drawing showing one embodiment of the invention merely for the purpose of illustration,

Referring to the drawing, there is illustrated part of the equipment for the transmission of signais between a distant ofce A1 and a subscriber-s loffice A2, the two offices being interconnected through a central oiiice CO. The teletypewriter T'I'Y1 of the distant oice A1 is connected over line L1, L2 to the winding of the relay Ri and a nontyping selector SE of welleknown type. The nontyping selector SE will be employed to control two relays R2 and R3, the relay R2 being used to connect the armature of the relay R1 to the subscribers loop L3, L4 to repeat the signals to the subscribers loop, and the relay R3 employed to disconnect the armature of relay R1 from the subscribers loop La, L4 when signaling is to be terminated. The subscribers ofce A2 includes a teletypewriter TTY2, a full-.wave rectifier FW and a relay R4, the relay R4 being operated when sigu nais are. to be received from omce A1 and to remain operated only until the last signal has been received from that oiiice. The relay R4 will control another relay R5 so as to connect the source of power L5 to the motor M of the teletypewriter TTYz.

When no signals are being transmitted from the distant omce A1 to the central ofice CO over the line L1., L2, the apparatus. at the central oice will be in the condition shown in the drawing. The battery B1 will be connected over the subscribers loop Ls, Li to the upper winding of relay R4 through the rectifier FW, the interconnecting circuit including battery Bi, resistor Z1, normal contact K1 of relay R2,A resistor Z2, conductor L3, teletypewriter TTYz, rectier element CRz, upper winding of relay R4, rectiiier elementr CRi, conductor L4 and ground. The current traversing the upper Winding oi relay Re will be of a reduced magnitude as, for example, 10 mils., but this current through the upper winding will be insuflicient to overcome the opposing eiect produced by the lower or biasing winding of relay R4 which continuously carries a heavier current of, for example, 20 mils. The biasing winding circuit includes, in addition to the lower winding ofrelay Ri, the resistor Z3, the battery B2 and ground. Under these conditions the armature of relay Ri will be on its contact S as shown, and relay Re will be unoperated. The source of power Le, which is controlled by relay R5, will therefore be disconnected from the motor M of the teletypewriter If a predetermined signal or signals are transmitted from the teletypewriter TTY1 of the distant office A1, over the line L1, L2,.the contact K2 will be closed momentarily in response Ato Vthe predetermined signal or signals. A signal that may be used for this purpose is, for example, Figs A or Figs A followed by Letters. The momentary closure of Contact K2 will cause relay R2 to be operated,.the operatingV circuit including battery B3, the winding of re-,

lay R2, the lower armature and make contact of relay R2, the armature and back contact of relay Ra and ground. In response to the operation of relay R2, thearmature of relay R1 will be connected to the conductor- Ls of the subscribers loop, the connection being completed through the upper armature of relay R2 vand the makebefore-break contact associated therewith. 1nasmuch as the winding of relay R1 receives all signals transmitted from the teletypewriter 'ITY1 of the distant office A1, its armature will move between its M and S contacts in response to these signals so as to connect oppositely poled batteries B4 and B5 alternately to the. conductor Ls ofv the subscribers loop through the upper armature of relay R2 and its make contact. The signals will then be received and recorded by the subscribers teletypewriter TTYz provided its motor M is in operation.

The motor M of the teletypewriter ,TTYz at the subscribers office A2 will be connected to its source of power L5 upon the operation of relay R2 as will now be explained.A In response to the i operation of relay R2 the battery B5 will be connected to the subscribers loop La, L4 over a circuit which includes battery B5, the armature and marking contact M of relay R1, the upper armature and make contact of relay R2, resistor Z2, conductor La, teletypewriter TTY2, rectifier Velement CR2, the upper winding of relay R4, rectitypewriter TTY2, rectifier element CRa, the upper winding of relay R4, rectier element CR4, conductor L4 and ground. The rectier elements CRs and CR4 are so poled as to cause the current suppliedby battery B4 to traverse the upper winding of relay R4 in the same direction as will current from battery B5. Consequently relay R4 will remain operated when the armature of relay R1 is on its spacing contact S. Hence relay R5 will remain operated and maintain the source of power L5 connected to the motor M of the subscribers teletypewriter TTY2.

It will be observed, therefore, that as signals are received by the relay R1 from the distant teletypewriterTTYn the connection of oppositely rpoled batteries to the subscribers loop La, L4

vwill cause current to traverse the upper or operating winding of relay R4 in the same direction fier element CR1, conductor L4 and ground. The

resistor Z2 is of a considerably smaller magnitude than resistor Z1 so that the current now traversing the upper winding of relay R4 will be of a substantially increased magnitude as,

. for example, 30 mils. The effect of this current flowing through the upper winding of relay R4 will be sufiicient to overcome theopposing effect of the lower or biasing winding of relay R4 and thereby cause the armature of relay R4 to close its contact M. When this happens, relay R5 will be operated, vthe operating circuit including battery B2, resistor Z4, the armature and contact M of relay R4, the winding of relay R5 and ground. Relay R5 will then connect the source of power L5 to the motor M and cause it to operate the teletypewriter TTY2 so that signals from the distant office A1 may be received and recorded by the subscribers teletypewriter T'IY2 in the usual manner,

When the relay R1 receives a spacing signal, for example, from the teletypewriter TTY1 of the distant oiiice A1, battery B4, which is of a polarity opposite to that of battery B5, will be connected to theconductor La and to the upper winding of relay R4 over a circuit which includes battery B4, the armature and spacing contact S of relay R1, the upper armature and make contact 4of relay R2, resistor Z2, conductor La, tele- R3, contact K3 and ground.

practically continuously and therefore maintain relay R4 operated. The travel time of the armature of polar relay R1 will be insucient to allow relay R4 to release. Relay R4 will therefore remain operated as long as relay R2 remains operated. Relay R5 will likewise remain operated as long as relay R2 remains operated. Thus the motor M will be maintained in its operated condition as long as relay R2 remains operated. The connection of the full-wave rectiier FW in circuit of the relay R4 to 'maintain the motor M in operated condition as long as the distant office A1 and the subscribers office A2 are interconnected for the transmission of signals, represents a primary feature of this arrangement.

When the transmission oi' signals from the distant teletypewriter TI'Y1 to the subscribers teletypewriter TTY2 is to be terminated, another predetermined signal or signals will be transmitted over the line L1, L2. This signal, which may be, for example, Figs H, will cause a momentary closure of contact K3. When Contact K2 is closed,.relay,Ra is operated over a circuit which includes battery B3, the winding of 'relay The operation oi' relay R3 will open the locking circuit for relay R2 theretofore provided by the back contact of the'armature of relay R3, and hence relay,` R2 will become released. Upon the release of relay R2 battery B1 will then be reconnected to the subscribers loop conductor L3 as shown in the drawing and as already described. The current supplied by battery Bi'to the upper winding of relay R4 through the full-wave rectifier will now be of reduced magnitude Ydue to the presence of both resistors Z1 and Z2 in the interconnecting circuit. In that case the armature of relay R4 will return to its Contact S, causing relay R5 to release. Relay R5 will then disconnect the motor M from the source of power L5.l

It is noted that the predetermined signal or signals to be employed for interconnecting the distant and subscribers offices A1 and A2 may be, for example, a character such as Figs A, or any series of characters such as l'igs A followed by Lettera etc. It is important to provide a pause after the 'contact K2 is closed to operate relaysk R2, R4 and R5 and allow the motor Mat the subscribers office to reach its required speed. This is important in that the receiving teletypewriter TTY2 is caused thereby to operate'in synchronism with the transmitting teletypewriter TTY1 even in reproducing and recording the rst signal of the message.' The predetermined.

starting signals transmitted to theapparatus of this invention are intended to 'cause `the teletypewriter T'I'Yz to receive signals only after the motor M has reached its rated speed.

It is noted that the oices A1 4and A2 are shown interconnected s that signals may be transmitted from the oice A1 and received by the oice Az. The equipment for the transmission of signals from ollce A2 to oiice A1 has been omitted merely to simplify the disclosure and illustrate only the apparatus necessary to understand the invention. It will be clear, however, that apparatus for the two-way transmission of signals between two or more oices is clearly contemplated and that the additional equipment for this purpose which is of well-known type need not be described.

The distant office A1 is shown connected to but one subscribers office A2. Additional ofices may be connected to the circuit in any well-known manner. For example, another office having a repeating relay such as R1 and a non-typing selector such as SE, may be connected in series with line L1, L2 so that all of the oices will be connected to the same circuit. If so desired, different predetermined characters may be employed to start or stop the motors of the teletypewriters at the dierent oiices, as will be understood by those skilled in the art.

The magnitude of the currents and the types of characters or signals that may be used in the operation of the equipment of this invention have been given merely for illustrative purposes. It

will be understood that the system may be de signed to operate with other current values and other characters or signals widely different from those referred to without departing from the spirit of the invention. Moreover, the invention may be readily applied to telegraph systems or to any system in which oppositely poled currents or voltagesare employed for signaling. The primary obiective of the invention is the maintenance of the operation of receiving equipment while the polarity of the current or voltage isl undergoing rapid changes. The invention may be employed wherever pulses of current are transmitted and it will serve to control the operation of equipment at the receiving point.

While this invention has been shown and described in certain embodiments merely for the purpose of illustration, it will be understood that the general principles of this invention may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a teletypewriter system, the combination of a rst teletypewriter, a full wave rectier, a second teletypewriter having a winding in series with said rectier and a motor to control the operation of said second teletypewriter, a biased relay connected to said rectifier to control the operation of said motor, an impedance element connected to said winding and said rectier so as to reduce any current traversing the relay below the value required for its operation, and means responsive to a predetermined signal to disconnect said impedance element from the circuit of said winding and said rectier, said latter means including means to enable said first teletypewriter to produce oppositely poled pulses according to teletypewriter signals to be transmitted to the winding of said second teletypewriter and said rectifier, said relay being continuously operated by said oppositely poled pulses traversing said rectifier.

2. In a teletypewriter system, the combination of a rst teletypewriter, a second teletypewriter for receiving signals from said iirst teletypewriter, said second teletypewriter having a winding and a motor, an impedance element, a full wave rectifier, a biased relay having its winding connected in circuit with said rectifier, said impedance element and said winding, said impedance element being of such a magnitude that currents traversing said relay will be insufcient to operate it, means responsive to a predetermined signal from said iirst teletypewriter to disconnect said impedance element from said circuit to enable oppositely poled pulses corresponding to signals from said first teletypewriter to be transmitted to the winding of the second teletypewriter, and means responsive to said predetermined signal to continuously operate said relay, said relay controlling the operation of the motor of said second teletypewriter.

3. In a teletypewriter system, the combination of a rst teletypewriter, a second teletypewriter having a winding and a motor, an impedance element, a full wave rectifier, a biased relay connected to said rectifier, a source of current connected through said impedance element to said winding and said rectifier, the magnitude of the latter current being insuiiicient to operate said relay, means controlled by said relay to operate said motor, means responsive to a predetermined signal to disconnect said source of current and said impedance element from said winding and said rectifier, said latter means including means for applying oppositely poled sources of current in accordance with signals from said irst teletypewriter to operate said relay continuously.

4. In a teletypewriter system, the combination of a rst teletypewriter, a second teletypewriter having a winding and a motor, an impedance element, a full wave rectifier, a biased relay connected to said rectifier, a source of current connected in circuit With said impedance element and said winding and rectifier, the magnitude of the latter current being insuicient to operate the relay connected to said rectifier, means controlled by said relay to operate said motor, means responsive to a rst predetermined signal from said first teletypewriter to disconnect said source of current and said impedance element from said circuit, said latter means including means responsive to teletypewriter signals from said rst teletypewriter for alternately applying oppositely poled sources of current through said winding to said rectifier so as to continuously operate the relay connected to said rectifier, and means responsive to a second predetermined signal to reconnect said source of current and said impedance element to said circuit to release said relay.

RUSSELL JACOB ANSPACH. CHARLES ROBERT WALKER. 

